Induction time of anesthesia and recovery of benzocaine to patinga (Piaractus mesopotamicus x Piaractus brachypomus)

In intensive fish farming, anesthetics are used in order to reduce stress fish during handling. This work was carried out to evaluate benzocaine as an anesthetic agent for patinga. Were used 60 fingerlings with an average weight of 2.08 +/- 0.30 g and total length of 4.56 +/- 0.23 cm. They were evaluated six different concentrations of benzocaine (50, 100, 150, 200, 250 and 300 mg L-1). The fish were individually exposed to anesthetic to evaluate the anesthetic induction, after the anesthesia procedure, the fish were transferred to aquaria with anesthetic free water, for observation of recovery time. Thereafter, the fish in each treatment were placed in tanks with 30 liters for monitoring the mortality during 72 hours. There was a significant difference (P<0.05) for the induction times and recovery room for different concentrations of benzocaine. Mortality was observed in animals anesthetic concentrations above 250 mg L-1. It concludes that benzocaine is effective in anesthesia fry patinga without causing damage to the concentration of 250 mg L-1. It is recommended using 150 mg L-1 benzocaine it presents efficiency and safety, without the need to use higher dosages.